The Do Not Honor error typically means your bank or credit card company is blocking the transaction.
We recommend you check with your bank or credit card company to see what the issue is before attempting again. Let them know the amount you're trying to charge and that you're attempting to make a purchase on Reverb.com, and they should be able to identify the problem and allow your next purchase attempt to go through.
If you're unable to successfully check out after contacting your bank, contact Reverb Support for further assistance.